


Ars cantus mensurabilis

by Beltenebra



Category: This is How You Lose the Time War - Amal El-Mohtar & Max Gladstone
Genre: Breaking News: Rogue Time Wives Still In Love, Epistolary, Established Relationship, F/F, Post-Canon, Time Travel
Language: English
Status: Completed
Published: 2020-12-19
Updated: 2020-12-19
Packaged: 2021-03-11 00:29:13
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,825
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28166274
Author URL: https://archiveofourown.org/users/Beltenebra/pseuds/Beltenebra
Summary: Ars cantus mensurabilis - the art of measured songorA playlist constructed over time
Relationships: Blue/Red (This is How You Lose the Time War)
Comments: 25
Kudos: 36
Collections: Yuletide 2020





	Ars cantus mensurabilis

**Author's Note:**

  * For [thearrogantemu](https://archiveofourown.org/users/thearrogantemu/gifts).



> Happy Yuletide, TheArrogantEmu! I was very happy to see your request and fortunate to snatch it from the pool. I kind of let my words run wild with this, I hope it helps make your holidays even a little brighter.

There are thousands of branching futures, countless ways for it to continue, a fathomless number of possible endings. 

But it started like this. 

Blue slipped through the river of students, a strong current of bodies streaming from one building to another. She was the flash of a silver salmon cutting through the current, heading upstream, deftly wending through the crowd to reach the music library of the Conservatory of Shanghai. 

A quietly murmured inquiry sent her down a flight of stairs to the first basement level where the microfiche machines are kept. A careful search of the catalogue lead her to the roll she needs and she scrolls through the articles, skimming and scanning until something caught her eye. 

It was a write up of an archeological discovery, a buried library in Suzhou. They discovered music texts hundreds of years old along with a cache of ancient instruments - flutes, and drums, and stringed instruments. As her eyes moved over the slightly fuzzed text in black and white and grey she saw the shape of a letter swim into being in the spaces between and a song embedded within. 

It was a sweeping melody, dramatic and lush, cold and clear and achingly sad - the reflection of the moon on an unbroken sweep of mountain snow. Voices wove through the flute and the strings singing about death come too soon, love realized too late, and surrendering one’s sadness to the moon. Blue could imagine Red’s deep sigh when she heard it, perhaps in a tea house in a city long gone. 

_Light of my heart, my lapis flame,_

_I know you are busy and while I would never willingly keep you from my side longer than necessary I couldn’t resist sending you on a little side quest while you were upstream in Strand 246. It’s not even out of your way and I’m sure you have already completed your task with ease. Doubtless you were able to ensure that the maestro’s exhibition went off without a hitch, no silly flood to get in the way of her grand triumph._

_I was thinking, perhaps even a touch nostalgically (a luxury that I am free to indulge in now that I have become disconnected as it were) of our past selves when we had both realized the fundamental truth of our situation but before we had realized our power to manifest it. A more melancholy time certainly, but sometimes contemplation of past sorrow deepens current joy. The shadow casts the light on the curve of your cheek into golden warmth and I know my heart will return to me in due time._

_Enjoy this and think of me in a distant past, inky robes marred only by the scarlet ribbon of my heart’s blood spilled by the steel of your sword, scored by the sound of a flute on a snowy wind._

_Yours in sorrow and joy,  
Red_

The flames licked up the stone walls, throwing their defiant heat into the chill air. Red and the occasional gust of snow were the only witnesses to the fire that devastated the workshop, windows popping loudly without, the groan of metal warping deep within. The compound she had sprayed on the surrounding buildings was working perfectly - the inferno raged within the bounds she had set for it and no further. 

The inventor would take the fire as a bad omen and turn her formidable mind from mechanical weapons to poison, still dangerous, to be sure. She would remain a midwife of violent deaths for decades to come but she would also unwittingly discover an alchemical process that would save millions of lives, causing ripples that reached far downthread. 

Flames throwing odd flickering shadows over her face, she stood and watched, enjoying the warmth until the building crumbled down to its stone skeleton and the only light came from the glowing coals. Only then did she turn the collar of her coat up against the cold and head deeper into the Old Town. 

Red had always enjoyed Prague. In most strands it remained intact and unbothered by the wars that toppled buildings and shattered streets and bridges in other European cities. The buildings of medieval stone were solid without being imposing, the people less stoic than some, the wine and pastries rich. 

That was something she had been making an effort to notice more, the flavor and texture of things - salty, sour, sweet, crunchy, unctuous, chewy. It was still a strange sensation, eating and drinking for pleasure but she was coming to like it. She purchased a trdelnik hot off the spit from a corner vendor and nibbled it as she walked, the sun slowly illuminating the morning streets. 

The city bustle caught up with her, silent morning easing into the lively hustle of the day. She meant to take one more turn through the square with a brief stop at the torture museum, a macabe personal favorite, before taking her leave but she stopped in her tracks when she saw it. 

A morpho menelaus, if she wasn’t mistaken (and she rarely was), it was nearly as far away from home as she was, in space if not in time. It alighted on a lamppost a few feet away and fluttered its wings coquettishly as if waiting to make sure she noticed. As if she could have missed it. Her eyes had long ago been trained to catch on every scrap and flash of the color from pale aquamarine to deep midnight. 

It moved as she drew even with it, staying just a few feet ahead, landing briefly on carts and sign posts and the occasional hat, leading her on a merry dance through the cobblestone alleys. Finally it perched on a discrete sign with lovely scrolling silver letters that read: Cerulean Siren Alchemy Lab ~ Parfumerie. 

Ah. 

The bell tinkled delicately as she entered the shop, summoning a lovely woman in a dark apron from the back. Red was greeted and presented with a bone china cup of strong coffee. She had been expected. As she sipped, the proprietress explained that she created bespoke fragrances only and after gathering some information she would choose and combine elements from the vast array they had available. 

Indeed the many shelves of the shop were lined with identical crystal vials bearing tiny, neat labels, the contents of some were colored but most were clear, catching even the weak winter light and throwing rainbows around the room. 

Red’s conversation with the woman was pleasant - she was asked many questions and answered very few of them anything close to truthfully. The questions ran out just as she had taken her final sip of coffee and set the cup back into the saucer with a quiet clink. 

The woman bid her return in six weeks time and she agreed. They shared a secret smile, the woman’s eyes twinkled knowingly and Red wondered how explicitly she was aware that six weeks for Red was quite unlike six weeks for her. 

Red left the shop with a tip of her hat and took a stroll around the block. Two minutes later, the sun considerably higher and the weather straining towards Spring, she let herself back in and was greeted warmly. 

The bottle she was presented with was faceted crystal like the others but round and jewel-like. The woman spritzed a light cloud into the slanting light and gestured for Red to lean in. Clean water and Japanese citrus, smoked cedar and steel, and somewhere deep under it all faint notes of the chill between stars. The scent tapered off with a final whiff, that made her laugh. Lavender, as sure a brand as a tattoo. 

“How did you know?” Red had given the woman nothing of her true self and yet… 

The woman tilted her head with fond amusement, “Oh rosebud, how do you think?”

Red held her hand out and the woman let the bottle drop into her palm, heavy and cool. She sprayed it again and let the song bloom around her, the disco pop groove and sultry crooned phrases at odds with the Victorian surroundings. She twirled in time with the chorus, already humming along as the letter sank into her skin. 

_My Parthian Thread,_

_I hope the fragrance meets your exacting standards. I have already taken to spraying the barest hint of it on my pillow to make my dreams sweet while you are away. Writers have compared love and music for time immemorial with varying degrees of eloquence but I think the bards of the twenty first century might have the best knack for it._

_I do not know exactly how to tally up days and weeks and months when we’re both on the move but I promise you that song will follow you a long way._

_I did not always appreciate the truth in a love song but I believe now I possess the necessary tools to compare my beloved to her own unique and treasured melody. Did not a prophet of the same time declare ‘my heart’s a stereo that only plays for you’? I shall follow my new directive, pouring the music of you through the instrument of me and beautifying the world._

_There’s a shop in the Old Town that sells nothing but gingerbread in a dizzying array of shapes and textures. You should bring some back with you._

_All of my love, (all of my love, oh all of my love to you),  
Blue_

It had been the work of a few days to establish herself as a mysterious, vaguely royal (everyone knew how tangled royal bloodlines could get) visitor from Corinth and earn herself an invitation to the Athenian senator’s latest grand dinner. She charmed his guests, flattered his wife, and gracefully extricated herself before the conversation could turn towards her own background. The senator’s wife cultivated lovely gardens after all, it would be unthinkable to visit such an august household without a turn about the courtyard. 

She admired the array of plants with a secretive smile, at least three of them would not have come into existence without her work on behalf of her former employer. It wasn’t long before a tentative cough broke the silence. The second son of the senator stood behind her, questions burning in his eyes. 

Blue had spent the last few hours of conversation expertly seeding her witty remarks with insinuations designed to catch the young man’s attention. This meandering conversation in an evening garden heady with hellebore and larkspur would light a spark that would, in time, fan itself into the steady flame of inspiration that would cause this young man to lead his city in a direction that would many many years later lead both Garden and the Agency further away from the safe spaces she and Red were nurturing for themselves. 

As she led the young man deftly through the steps of the verbal dance he paused, gesturing to a passing house slave to attend them. They refilled her goblet with the pale gold wine of the hills, and proffered a wide rimmed dish of spiced honey drenched figs. She was casually reaching for one when she noticed the design chased around the dish in perfect geometry, a rich deep lapis. 

She saw the letter in every achingly crisp corner of the design, and tucked the words and music into the secret curve of her smile for later before turning her attention back to her companion. 

Hours later when the host and hostess had retired, the last few guests sprawled on couches sleeping the sleep of the deeply drunk, and the thoughtful second son was dreaming of a brighter, more equitable future, she returned to the garden. Her fingers traced the design on the now empty dish, trailing the tips through the dregs of honey and spice, licking them clean as the pure voice of a clarinet fluttered flirtatiously, sliding up through a glorious glissando just before the orchestra burst forth like fireworks. 

The rhythm of the letter tapped and swung as exuberantly as the music. 

_Tangled up in Blue,_

_I have no doubt your work is going well. The senator and his guests are surely smitten with your beauty and wit. You always did have far more patience than I in wielding the subtle stiletto of conversation._

_I offer a return gift for you, my sapphire delight, as the strains of your previous present still echo in my head. A much more pleasant type of earworm than the ones from Ceti Alpha 5 in Strand 198 to be sure._

_It’s possible I shouldn't have introduced this particular pigment this far upstream in this strand, it may come to haunt me eventually, I suppose we shall see! But how could I allow the opportunity to wax rhapsodic, as it were, pass me by? Rhapsodic, get it? Oh, stop making that face. No no, I kid - never stop making that face._

_This music with all of its sinuous turns and fantastic bombast reminded me of raucous neon nights with you by my side. Paris, Strand 369, perhaps? The arc of the water flung like diamonds as you leapt into the fountain never doubting I would follow right behind you. You are my city, the riotous, tripping rhythm of my heart._

_Yours in the rocking sway of every streetcar,  
Red_

She stalked her target soundlessly through corridors hung with lavish swags of rich cloth, long halls lined with alcoves designed for private, if brief, assignations. The man never saw her coming, the needle slid soundlessly out from its casing beneath her nail and disappeared a breath later. The systems embedded under her skin that had synthesized the poison now monitored its progress through her target’s system. He died quickly, gasping harshly for air, hands scrabbling uselessly at plush brocade walls. 

Red drew the curtain over the alcove and slipped easily back into the eddy of the crowd, swirled into the heart of the celebration whirling giddily through the ballroom. The party goers would never know just how fatale a femme she had really been. 

An ornate hourglass parceled time into a shimmering trickle, counting down the hours of the longest night of the year. The city’s most prestigious courtesans glided gracefully through the crowd, a flock of birds in dazzling plumage. They were staggeringly lovely, gowns and jackets cut to show off elaborate tattoos winding down backs, symbols of their stature. 

A beautiful man with verdant jade-shaded eyes pressed a tiny crystal goblet into her hands before winking and melting back into the crowd, allowing her only a glimpse of the vivid blue heliotrope snaking down his spine. Party goers held their glasses aloft as the final grains of sand fell and the night turned round towards day. The hall rang out with wishes of joy in the next year and glasses were brought to lips. 

Red tossed the clear liqueur back in one swift swallow, her vision sparkled as the bright rush of flavor overtook her senses. She could taste the tiny garnet berries encased in ice that were pressed for juice, the dense pine of the snow covered forest as it burst on her tongue, intertwined with the wave of words and sound that was the letter. 

The music washed over her, carrying a memory - the cold metal of the deck under her feet, the gallery of the ship flooded with indigo, violet, magenta, the light of a new galaxy. They had been drawn by the energy of its birth, and stayed to watch, entranced by the asteroid sized creatures that glided and splashed in the star shine sea and called to each other across space, haunting and lovely. A hand in hers and a hushed wonder, beautiful beyond measure for the sharing. 

_My Scarlet Pimpernel,_

_I can still see the shine of the eight moons reflected on the astral waves and in your dark eyes. The echoes of these moments, ripples of joy we have left behind, trailing like a comet's tail up and down the stream, this is what sustains me when I am far away from you spatially and temporally._

_As I travel to the next turning point, the nexus, the lynchpin of a more stable future, in my mind I'm treading the steps of our courtship, tracing the path through the labyrinth of my heart as it bends toward yours. Already I am thinking about my next gift, a moment of pleasure that can equal the shine of the jewels you have already strewn in my path, my clever cardinal._

_I hope you are enjoying the celebration. I know that fancy dress parties are not your first inclination for distraction but you do love a good old-fashioned murder (on behalf of the right cause). Surely you have completed your mission with plenty of time to spare for entertainment. Pluck whatever night blooming flower catches your fancy, only return to me, my magnetic north, my compass rose._

_With love like the horizon,  
your Blue sky_

When her research took her to Munich in Strand 23 in the summer of 1865 Blue already had a hunch about what she might find. Sure enough, just as she had completed her errand a messenger rounded the corner and pressed an envelope into her hand with a flashing grin and a tip of his hat. She tucked the package she had intercepted, a packet of correspondence meant for a high level minister and intended to be used as blackmail of several prominent figures safely into her coat, and slid her thumbnail along the flap of the envelope, breaking the seal of crimson wax stamped with a stylized R to find a ticket to the opera.

Blue spent the afternoon dress shopping.

The National Theatre was resplendent, chandeliers sparkling, scattering dazzling patterns of light over gold gilded fixtures, the excited hum of Munich's elite streaming into the building. An usher swept the curtain leading to her box open with a deep bow and a waiter stood by waiting to pour the champagne.

Six chairs were lined up smartly in two rows, plush crimson velvet and handsome mahogany, all unoccupied but Blue but she knew which chair was meant for her. Without prompting from the usher, she swept the cerulean fall of her gown up and settled into the middle seat in the first row like a flower unfolding its petals and leaned forward to survey the theater. The view was unparalleled.

She sipped Dom Perignon and enjoyed watching the patrons making their way to their seats. she found the letter as the orchestra was tuning up - elegantly carved vines, curling down the wood of the right arm of her chair resolved into phrases under her questing fingertips but the first one stated clearly: Wait for Act 2! So she waited.

The intended moment was very clear. As Tristan and Isolde, at last freed from the constraints of the court and far from prying eyes, gave in to their passion and declared their love, her fingers traced the wooden whorls and let the letter unfurl around her like the music that filled the hall.

_Blue Jay Way,_

_Ah how I wish I was there beside you, the velvet of my coat falling over the folds of your gown, making violet shadows. I couldn't quite make the premiere but I'll tell you a secret, I am in the seat to your left (your sinister counterpart to the last) in the very same theater, only a hundred and fifty six years late. Can you feel the ghost of my hand twined with yours, beloved? Can you see the afterimage of my smile in the reflected stage lights? Even as I weep for the lovers (there's not a dry eye in the house here, how about yours?) my lips can not refuse that expression of helpless joy when you are near._

_I'd pour you another glass of champagne if I were then, my love. Crying is thirsty work. Shall we raise a glass to a hopeless cause? Our paramours here seemed to think the only release from their torment was death. It's a good thing we're quicker on our feet for I want nothing more than to pass time trading words and sounds and meaning with you, entwining the threads of manifold worlds to wrap you in the tapestry of our story._

_May the forgiving night we are weaving around us last forever, never to be pierced by the harsh spear of day and the sorrow of a jealous king._

_With love from the far side of despair,  
Red_

There were many avenues to influence in politics and Red had employed all of them in her long career, exploring their endless themes and variations. The end she needed to achieve was prevention of a seemingly harmless piece of legislation, the passing or failing of which would not be the cause of particularly strong emotions. If left to pass however, this innocent statute would lead to the nearly unstoppable rise of a ruthless authoritarian police state. 

She had been able to solve the problem by bribing two unremarkable members of the House of Lords - neither of them possessing status either low or high enough to be of note and both quite happy to be bought off. The vote went smoothly, strangling the fledgling law in infancy before it would have the chance to grow into vicious, twisted maturity. 

One of the lords invited her to a large dinner party at his Chelsea manner with half an eye on creating the appearance of an association between them if anyone bothered to look into it but mostly on a lark. It had been a long time since Red had indulged in the delights of the roaring twenties, she gave into the whim and accepted. 

Dinner was merely above average, but the gin was exquisite. She escaped from the table as soon as it was polite to do so, wandering through the parlour designated for dancing and enjoying the live jazz combo before moving on, eventually finding herself in what seemed to be either a large study or small library. 

There was a gramophone in a dim corner and a disc in a plain crimson sleeve. She flipped the switch on a nearby table lamp to get a better look and found the letter, a glowing patchwork pattern spread across the wood by the Tiffany shade. Committing it to memory to read later she slid the unmarked disc free of its envelope and placed the needle. 

The song was so straightforward, undeniably charming in its candor and so far from Blue’s habitual delicacy that it startled a laugh out of her. The sound drew the lord of the manor and she was forced to hastily secret the disc between bulky atlases. Fortunately she was able to maneuver her way out of further social obligations and unbeknownst to the host and hostess, while the rest of the company were occupied with brandy and cigars she crept back to the study to listen over and over again. 

The melody was soft and sweet, she felt herself drawn in by the sentiment and the clock ticking like a heartbeat behind them. It was the kind of music she would have mocked in the time before she knew what it was like to feel the truth of such phrases like fire in her veins. Had love made her softer? No, if anything she pursued her goals with more ruthless efficiency. Red in tooth and claw, and fierce in the protection of this beautiful thing they were nurturing between them. 

She admired the cut glass design, a blue green dragonfly alighting on a poppy, and read the letter. Let their enemies come, she’d be waiting. 

_Bright hooded darling, slayer of wolves,_

_It’s a little on the nose I’ll admit, but I imagine it amused you. I’ll tuck the sound of your unguarded laughter close to my heart and save it for a darker moment._

_I’m on the trail of a story, hunting a particularly slippery legend upthread and down and while it is eluding me, I have found dozens of tales I want to share with you. Foreboding forests and slumbering castles, cunning creatures and reluctant royalty, white snow and the red, red rose._

_I would write our story in the comforting finality of a fairy tale, taking nothing for granted, simple in its language and steeped in fundamental truth. The kind of story that once you hear it, you can not imagine the world was any other way. I would make us irrefutable, my red dawn, my cherry heart._

_Someday I will collect all of the futures where we are not together, gather them like a bouquet and illuminate them, bind them in butter soft leather… and consign them to a fire to match the one in your eyes._

_If you fall, I will catch you,  
Blue_

Soft dark robes swirled around her feet as Blue glided through the halls of Trinity College. The deep throb of the bells rang the end of vespers, many denizens of the college would be making their way to the chapel for evening prayers. 

The late summer sun would linger near the horizon for another hour and the mingling of the newly lit lamps and the red gold of the dying light caught her breath. If only she had more time to linger, stalking the endless ranks of shelves for choice tidbits, delving into the stacks for rare monographs. But she was after something specific and it was unclear how much time she had. 

Red had started this game and Blue had been thrilled to continue it, the delightful push and pull, hidden letters and music buried like land mines in each other’s expected paths. And so turn by turn, move and counter, they climbed up and down the strands of history, plucking shining threads of melodies from the braid and weaving them together into a tapestry, a bracelet, a _ring_ \- the two of them enclosing each other in perpetuity. 

Their old habit of coding letters in seeds, in feathers, in unmelting Arctic ice shifted only a little as they chose sounds and imbued them with more personal meaning. Music has always been a message from one heart to another and they were hardly the first to use it thus. 

Her love had seemed particularly excited when she hinted at her last clue, dropped as casually as one’s keys into the bowl by the door at the end of the day. Blue didn’t know exactly what was coming next but she delighted in trying to stay one step ahead of her paramour. She tugged her hood forward, throwing her face into deeper shadow and moved with renewed purpose. 

She found the treatise without much trouble, only about four hundred years old at this point in the thread, the pages starting to brittle with age but still supple enough to be handled carefully. 

Ars cantus mensurabilis contained Franco of Cologne’s many theories on the sacred art of music. It had no fewer than three hundred and forty seven pages and five appendices. Appendix three seems to be an index made up of one page: a beautifully scribed list of the many songs they have been sending each other, one after another flowing down the parchment, the jumble of languages both terribly strange and surprisingly perfect in the scholarly scribal hand. 

When she gingerly turned the pages to the section of the book referenced in index three, a definition of measured music and theories of what exactly “tempus” is, she found a grey plastic cassette tape. The case was plain save two painted birds: on one side a brilliant blue jay, on the other a crimson cardinal. It opened with a soft snick revealing the cassette and a single sheet of white and blue lined paper folded into quarters, the left edge rough as if it had been freshly torn from its notebook only a moment ago. 

The ballpoint pen scrawl was achingly familiar. 

_Most fragrant hyacinthoides non-scripta,_

_I am sure you are aware, dearest, that measurements when it comes to music are of course, regarding time. I can think of no better conveyance of my feelings than sounds moving through the element as essential to us as breath._

_Particular notes in particular patterns, phantoms that shall echo the stirrings of my heart in relation to yours up and down every thread of every strand until all of the suns in all of the eventualities are extinguished and every possible waveform has collapsed. May we be fortunate enough to witness it together, hands clasped tight._

_Delicate though my sentiments may be, it is still part of my nature to compile data and ruthlessly marshal it into formal shape and structure. And so I have done with our chosen declarations, compiling them here for your immediate review and approval..._

_Come home, my love. I just put fresh batteries in the boombox._

**Author's Note:**

> I tried to seed enough clues about the songs throughout each section that guessing what they are might be a fun game. If you decide to play, please leave your guesses in the comments as I would very much like to see them! Also let me know if/when you would like them confirmed. 
> 
> Feel free to come yell with me about all things literary (and many other random topics) on twitter [@the_bel_tolls](https://twitter.com/the_bel_tolls)!
> 
> If you'd like to share this fic, it's easily retweetable from [here](https://twitter.com/the_bel_tolls/status/1345072074507898885?s=20)


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